The Experts below are selected from a list of 14784 Experts worldwide ranked by ideXlab platform
L A Orozco - One of the best experts on this subject based on the ideXlab platform.
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rayleigh scattering in an optical nanofiber as a probe of higher order mode propagation
arXiv: Quantum Physics, 2015Co-Authors: Jonathan E Hoffman, Fredrik K Fatemi, G Beadie, S L Rolston, L A OrozcoAbstract:Optical nanofibers provide a rich platform for exploring atomic and optical phenomena even when they support only a single spatial mode. Nanofibers supporting higher-order modes provide additional degrees of freedom to enable complex evanescent field profiles for interaction with the surrounding medium, but local control of these profiles requires Nondestructive evaluation of the propagating fields. Here, we use Rayleigh scattering for rapid measurement of the propagation of light in few-mode optical nanofibers. Imaging the Rayleigh scattered light provides direct visualization of the spatial evolution of propagating fields throughout the entire fiber, including the transition from core-cladding guidance to cladding-air guidance. We resolve the interference between higher-order modes to determine local beat lengths and modal content along the fiber, and show that the modal superposition in the waist can be systematically controlled by adjusting the input superposition. With this diagnostic we can measure variations in the radius of the fiber waist to below 3 nm in situ using purely optical means. This Nondestructive Technique also provides useful insight into light propagation in optical nanofibers.
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rayleigh scattering in an optical nanofiber as a probe of higher order mode propagation
Optica, 2015Co-Authors: Jonathan E Hoffman, Fredrik K Fatemi, G Beadie, S L Rolston, L A OrozcoAbstract:Optical nanofibers (ONFs) provide a rich platform for exploring atomic and optical phenomena even when they support only a single spatial mode. Nanofibers supporting higher-order modes (HOMs) provide additional degrees of freedom to enable complex evanescent field profiles for interaction with the surrounding medium, but local control of these profiles requires Nondestructive evaluation of the propagating fields. Here, we use Rayleigh scattering for rapid measurement of the propagation of light in few-mode ONFs. Imaging the Rayleigh scattered light provides direct visualization of the spatial evolution of propagating fields throughout the entire fiber, including the transition from core–cladding guidance to cladding–air guidance. We resolve the interference between HOMs to determine local beat lengths and modal content along the fiber, and show that the modal superposition in the waist can be systematically controlled by adjusting the input superposition. With this diagnostic we can measure variations in the radius of the fiber waist to below 3 nm in situ using purely optical means. This Nondestructive Technique also provides useful insight into light propagation in ONFs.
Mark N Merzlyak - One of the best experts on this subject based on the ideXlab platform.
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three band model for noninvasive estimation of chlorophyll carotenoids and anthocyanin contents in higher plant leaves
Geophysical Research Letters, 2006Co-Authors: Anatoly Gitelson, Galina P Keydan, Mark N MerzlyakAbstract:[1] Leaf pigment content and composition provide important information about plant physiological status. Reflectance measurements offer a rapid, Nondestructive Technique to estimate pigment content. This paper describes a recently developed three-band conceptual model capable of remotely estimating total of chlorophylls, carotenoids and anthocyanins contents in leaves from many tree and crop species. We tuned the spectral regions used in the model in accord with pigment of interest and the optical characteristics of the leaves studied, and showed that the developed Technique allowed accurate estimation of total chlorophylls, carotenoids and anthocyanins, explaining more than 91%, 70% and 93% of pigment variation, respectively. This new Technique shows a great potential for noninvasive tracking of the physiological status of vegetation and the impact of environmental changes.
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assessing carotenoid content in plant leaves with reflectance spectroscopy
Photochemistry and Photobiology, 2002Co-Authors: Anatoly Gitelson, Olga B. Chivkunova, Yoav Zur, Mark N MerzlyakAbstract:Spectral reflectance of maple, chestnut and beech leaves in a wide range of pigment content and composition was investigated to devise a Nondestructive Technique for total carotenoid (Car) content estimation in higher plant leaves. Reciprocal reflectance in the range 510 to 550 nm was found to be closely related to the total pigment content in leaves. The sensitivity of reciprocal reflectance to Car content was maximal in a spectral range around 510 nm; however, chlorophylls (Chl) also affect reflectance in this spectral range. To remove the Chl effect on the reciprocal reflectance at 510 nm, a reciprocal reflectance at either 550 or 700 nm was used, which was linearly proportional to the Chl content. Indices for Nondestructive estimation of Car content in leaves were devised and validated. Reflectances in three spectral bands, 510+/-5 nm, either 550+/-15 nm or 700+/-7.5 nm and the near infrared range above 750 nm are sufficient to estimate total Car content in plant leaves Nondestructively with a root mean square error of less than 1.75 nmol/cm2.
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optical properties and Nondestructive estimation of anthocyanin content in plant leaves
Photochemistry and Photobiology, 2001Co-Authors: Anatoly Gitelson, Mark N Merzlyak, Olga B. ChivkunovaAbstract:Abstract Absorption and reflectance spectra of maple (Acer platanoides), cotoneaster (Cotoneaster alaunica), dogwood (Cornus alba) and pelargonium (Pelargonium zonale) leaves with a wide range of pigment content and composition were studied in visible and near-infrared spectra in order to reveal specific anthocyanin (Anth) spectral features in leaves. Comparing absorption spectra of Anth-containing and Anth-free leaves with the same chlorophyll (Chl) content, absorption spectra of Anth in leaves were derived. The main spectral feature of Anth absorption in vivo was a peak around 550 nm; the peak magnitude was closely related to Anth content. A quantitative Nondestructive Technique was developed to subtract Chl contribution to reflectance in this spectral region and retrieve Anth content from reflectance over a wide range of pigment content and composition. Anth reflectance index in the form ARI = (R550)−1 − (R700)−1, where (R550)−1 and (R700)−1 are inverse reflectances at 550 and 700 nm, respectively, all...
Anatoly Gitelson - One of the best experts on this subject based on the ideXlab platform.
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three band model for noninvasive estimation of chlorophyll carotenoids and anthocyanin contents in higher plant leaves
Geophysical Research Letters, 2006Co-Authors: Anatoly Gitelson, Galina P Keydan, Mark N MerzlyakAbstract:[1] Leaf pigment content and composition provide important information about plant physiological status. Reflectance measurements offer a rapid, Nondestructive Technique to estimate pigment content. This paper describes a recently developed three-band conceptual model capable of remotely estimating total of chlorophylls, carotenoids and anthocyanins contents in leaves from many tree and crop species. We tuned the spectral regions used in the model in accord with pigment of interest and the optical characteristics of the leaves studied, and showed that the developed Technique allowed accurate estimation of total chlorophylls, carotenoids and anthocyanins, explaining more than 91%, 70% and 93% of pigment variation, respectively. This new Technique shows a great potential for noninvasive tracking of the physiological status of vegetation and the impact of environmental changes.
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assessing carotenoid content in plant leaves with reflectance spectroscopy
Photochemistry and Photobiology, 2002Co-Authors: Anatoly Gitelson, Olga B. Chivkunova, Yoav Zur, Mark N MerzlyakAbstract:Spectral reflectance of maple, chestnut and beech leaves in a wide range of pigment content and composition was investigated to devise a Nondestructive Technique for total carotenoid (Car) content estimation in higher plant leaves. Reciprocal reflectance in the range 510 to 550 nm was found to be closely related to the total pigment content in leaves. The sensitivity of reciprocal reflectance to Car content was maximal in a spectral range around 510 nm; however, chlorophylls (Chl) also affect reflectance in this spectral range. To remove the Chl effect on the reciprocal reflectance at 510 nm, a reciprocal reflectance at either 550 or 700 nm was used, which was linearly proportional to the Chl content. Indices for Nondestructive estimation of Car content in leaves were devised and validated. Reflectances in three spectral bands, 510+/-5 nm, either 550+/-15 nm or 700+/-7.5 nm and the near infrared range above 750 nm are sufficient to estimate total Car content in plant leaves Nondestructively with a root mean square error of less than 1.75 nmol/cm2.
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optical properties and Nondestructive estimation of anthocyanin content in plant leaves
Photochemistry and Photobiology, 2001Co-Authors: Anatoly Gitelson, Mark N Merzlyak, Olga B. ChivkunovaAbstract:Abstract Absorption and reflectance spectra of maple (Acer platanoides), cotoneaster (Cotoneaster alaunica), dogwood (Cornus alba) and pelargonium (Pelargonium zonale) leaves with a wide range of pigment content and composition were studied in visible and near-infrared spectra in order to reveal specific anthocyanin (Anth) spectral features in leaves. Comparing absorption spectra of Anth-containing and Anth-free leaves with the same chlorophyll (Chl) content, absorption spectra of Anth in leaves were derived. The main spectral feature of Anth absorption in vivo was a peak around 550 nm; the peak magnitude was closely related to Anth content. A quantitative Nondestructive Technique was developed to subtract Chl contribution to reflectance in this spectral region and retrieve Anth content from reflectance over a wide range of pigment content and composition. Anth reflectance index in the form ARI = (R550)−1 − (R700)−1, where (R550)−1 and (R700)−1 are inverse reflectances at 550 and 700 nm, respectively, all...
Jonathan E Hoffman - One of the best experts on this subject based on the ideXlab platform.
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rayleigh scattering in an optical nanofiber as a probe of higher order mode propagation
arXiv: Quantum Physics, 2015Co-Authors: Jonathan E Hoffman, Fredrik K Fatemi, G Beadie, S L Rolston, L A OrozcoAbstract:Optical nanofibers provide a rich platform for exploring atomic and optical phenomena even when they support only a single spatial mode. Nanofibers supporting higher-order modes provide additional degrees of freedom to enable complex evanescent field profiles for interaction with the surrounding medium, but local control of these profiles requires Nondestructive evaluation of the propagating fields. Here, we use Rayleigh scattering for rapid measurement of the propagation of light in few-mode optical nanofibers. Imaging the Rayleigh scattered light provides direct visualization of the spatial evolution of propagating fields throughout the entire fiber, including the transition from core-cladding guidance to cladding-air guidance. We resolve the interference between higher-order modes to determine local beat lengths and modal content along the fiber, and show that the modal superposition in the waist can be systematically controlled by adjusting the input superposition. With this diagnostic we can measure variations in the radius of the fiber waist to below 3 nm in situ using purely optical means. This Nondestructive Technique also provides useful insight into light propagation in optical nanofibers.
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rayleigh scattering in an optical nanofiber as a probe of higher order mode propagation
Optica, 2015Co-Authors: Jonathan E Hoffman, Fredrik K Fatemi, G Beadie, S L Rolston, L A OrozcoAbstract:Optical nanofibers (ONFs) provide a rich platform for exploring atomic and optical phenomena even when they support only a single spatial mode. Nanofibers supporting higher-order modes (HOMs) provide additional degrees of freedom to enable complex evanescent field profiles for interaction with the surrounding medium, but local control of these profiles requires Nondestructive evaluation of the propagating fields. Here, we use Rayleigh scattering for rapid measurement of the propagation of light in few-mode ONFs. Imaging the Rayleigh scattered light provides direct visualization of the spatial evolution of propagating fields throughout the entire fiber, including the transition from core–cladding guidance to cladding–air guidance. We resolve the interference between HOMs to determine local beat lengths and modal content along the fiber, and show that the modal superposition in the waist can be systematically controlled by adjusting the input superposition. With this diagnostic we can measure variations in the radius of the fiber waist to below 3 nm in situ using purely optical means. This Nondestructive Technique also provides useful insight into light propagation in ONFs.
Sophie Brasselet - One of the best experts on this subject based on the ideXlab platform.
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thioflavine t and congo red reveal the polymorphism of insulin amyloid fibrils when probed by polarization resolved fluorescence microscopy
Journal of Physical Chemistry B, 2013Co-Authors: Julien Duboisset, Patrick Ferrand, Wei He, Xiao Wang, Herve Rigneault, Sophie BrasseletAbstract:Amyloid fibrils are protein misfolding structures that involve a β-sheet structure and are associated with the pathologies of various neurodegenerative diseases. Here we show that Thioflavine-T and Congo Red, two major dyes used to image fibrils by fluorescence assays, can provide deep structural information when probed by means of polarization-resolved fluorescence microscopy. Unlike fluorescence anisotropy or fluorescence detected linear dichroism imaging, this Technique allows to retrieve simultaneously both mean orientation and orientation dispersion of the dye, used here as a reporter of the fibril structure. We have observed that insulin amyloid fibrils exhibit a homogeneous behavior over the fibrils' length, confirming their structural uniformity. In addition, these results reveal the existence of various structures among the observed fibrils' population, in spite of a similar aspect when imaged with conventional fluorescence microscopy. This optical Nondestructive Technique opens perspectives for in vivo structural analyses or high throughput screening.